Track building with functional plastic chairs

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JFS
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Track building with functional plastic chairs

Postby JFS » Wed Apr 10, 2013 8:28 am

Hope everyone found something useful in last night's session - sorry it went on a bit longer than usual and thanks for sticking it out to the bitter end!

I found that I was abusing David and Martin by accusing them of leaving the Template on the hall table - they actually left it in the loft.... :D

Since we did not get to finish the job last night, I will take some pics and wirte up some notes to post here if people think that would be of value.

Best wishes,

Howard.

bevis
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Re: Track building with functional plastic chairs

Postby bevis » Wed Apr 10, 2013 9:17 am

Yes, thanks Howard it was inspiring.
I think you need better staff. How could they leave things in the loft; dock their pay!
Regards,
Bevis

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Wed Apr 10, 2013 6:10 pm

Thanks Bevis - and I quite agree... :D

Just one thing I should have mentioned last night - I was singing the praises of Studiolith rail, but I should have mentioned that (after 40 years) it tends to be covered in a sticky goo which needs removing with some white spirit before you try to use it, Also, I had spent a fair bit of time cleaning off all the tarnish with a glass fibre brush - if you omit that step, you might find soldering it a bit of a challenge!

Managed to get half an hour to finish the switch I started last night.

Herewith a few pics

First of all, having polished up the switch blade, a trial fit against the stock rail

Switch Blade.jpg


Next, make the switch anchor from 0.7mm N/S wire, bent and filed to shape, and mark and drill the holes in both rails.

Switch Anchor prep.jpg


Next, having checked the fit, the switch anchor is soldered into the stock rail.

Switch Anchor ready.jpg


Then, the all important 1PL chair is slid in place along with some temporary running rail chairs to hold the rails in the correct inclination and relative height, and the switch blade is soldered to the switch anchor. The hair clip keeps the switch against the stock rail - the transition between the 1:20 inclination of the stock rail to that of the closure rail will take place at the joint between the blade and the closure rail - without this joint the switch needs a twist in it otherwise there will be a gap between the top edge of the switch and that of the stock rail - which we do not want!

Switch Anchor.jpg


I'll post a few more pics showing the assembly process over the next few days.

Best wishes,

Howard.

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Wed Apr 10, 2013 6:20 pm

... just a couple more showing the finished assembly.

Firstly one which - I hope - shows the profile of the end of the blade.

Assembly 4.jpg


Here is one trying to squint along the length to show that the curve runs through the switch assembly and how the set is made at the end of the blade (as the last operation) Sorry I am not much good at this taking pictures lark (where is Steve when you need him?)

Assembly.jpg
Assembly.jpg (50.68 KiB) Viewed 5078 times


In truth, the fit to the stock rail could be better - my excuse is that it is an "A" switch and I did say my jig only went down to a "B"...

Cheers,

H

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Bigfish
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Re: Track building with functional plastic chairs

Postby Bigfish » Thu Apr 11, 2013 8:26 am

Thanks Howard for a tremendously interesting presentation. Herewith our subsequent exchange on "droppers" and "set in the stock rails" in case this is of interest to readers of this thread:

Q1) due to the dropper pins you were using being chrome-plated, I gather you grind the heads off so you can replace the head with a solder-blob presumably in direct contact with the brass you've exposed by grinding? So do you do likewise with the sharp end in order to solder it for electrical purposes? I assume you've tried and rejected brass or n/s wire - too soft/bendable while putting assembly in place?
A: 1. YES - should have said so! Also should have also said that normally I do use unplated brass pins but these are quite hard to get hold of these days - I get mine from Hornsby's lace supplies (http://myweb.tiscali.co.uk/djhornsby/Home.htm) I had to use the others in this case as the brass pins are not long enough for the thickness of the baseboard. The problem with wire is that you need to bend over the end in order to get a good surface area in contact with the rail - a filed-flat pin head gives more area with extending beyond the confines of the chair.

Q2) any hints on making the set in the stock rails - ie are you just relying on matching by eye the miniscule wobble which Templot produces, or have you a more accurate way of matching the planing angle?
A: Re making the set, the bend has to be to the same angle as the switch planing. What happens in practice is that when you tweak the stockrail to be in full contact with the switch blade, the heel end is out of line with the Template - the set has to be just what is needed to just bring the rail back over the Template line.

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Martin Wynne
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Re: Track building with functional plastic chairs

Postby Martin Wynne » Thu Apr 11, 2013 3:16 pm

Bigfish wrote:Q2) any hints on making the set in the stock rails - i.e. are you just relying on matching by eye the miniscule wobble which Templot produces, or have you a more accurate way of matching the planing angle?

Adjust it to match the stock gauge where marked on the template (at the end of the planing). At that position it should be one rail-width greater than the track gauge. Here is a beginner getting it right on his first turnout:

http://www.modelrailforum.com/forums/in ... t&p=296201

Martin.
40 years developing Templot. And counting ...

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Thu Apr 11, 2013 6:10 pm

Hi Martin and many thanks for this.

Your link shows the tried and trusted approach - why would it not give perfect results every time? :D Or asking the question another way, why are there so many derailments at switches on P4 trackwork? Well, many things to go wrong of course, but for me, the approach of fixing both stock rails first then fitting the switches is the weakest aspect of the MRSG trackbuilding method and tends inevitably to a risk of tight gauge for beginners as they tend to leave too much meat on the switch blades, then locate the position of the switch by reference to its toe end. Perhaps even worse, if a switch is left a bit thick relative to the angle of the stock rail, there is a risk of the blade closing in the middle of the planing but leaving a gap at the toe - another route to frustration.

I was explaining an alternative approach where each switch / stockrail is made as a unit (as per the picture) - thus the unit can be picked up / squinted along / adjusted and tweaked until it is spot-on perfect, and should it fail to get there, it can be lobbed in the scrap - tricky if you have already soldered the stock rail to half a million rivets!. The idea is then that the two units can be gauged off the respective gauge faces throughout the toe area and the switches. When you do it this way, you can locate the set (along the length of the rail) by reference to the toe end of the switch. The extent of the set is the amount required to align the rails to the Template given the actual shape of the switch filing. I find that doing things in this order is much less likely to result in an under-gauge condition anywhere through the switches - which we have all done at some time with the traditional method (well, alright - I have!)

It might be worth pointing out that the picture above illustrates a trap point - in the example I showed at the meeting the stock rail was made full-length as it was a "proper" turnout.

Hope that sets the context for Alan's question.

Best wishes,

Howard.

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Russ Elliott
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Re: Track building with functional plastic chairs

Postby Russ Elliott » Fri Apr 12, 2013 1:05 am

I agree with much of your analysis and approach, Howard, and the idea of making the switch assemblies 'off-timber' so that they can conveniently examined and tweaked is one of those blindingly obvious "now why hasn't that been thought of before?" notions, but I feel you haven't followed through on the undergauge problem area, which is invariably on the divergent route, not the straight route. One could suggest that the obvious sequence of assembly should therefore be as follows, although your combined assemblies would be a '1+2' and '3+4':

switch-curve3.png
switch-curve3.png (5.39 KiB) Viewed 4838 times


The TG + 0.1 setting will result in the set of the diverging stock rail starting a couple of mm before it should, but who's going to be bothered about that?

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 12:47 pm

Russ,

Many thanks for adding this - I fully agree and I should have directed people to the CLAG article! As you say - the position of the set is (within reason) dictated by the geometry - blade shape, gauge widening etc hence it is best created at a late stage in the process.

Just one question thinking about the geometry however - in the event that both blades were machined perfectly and identically, is the implication of your approach that the straight road would also be over gauge? Alternatively, if the straight road were to perfect gauge then would there be an implication that the blades would be staggered by a small amount (ie, the straight road switch moved towards the toe a bit)? The third alternative would be a 0.1 mm gap at the back of the switch (4 thou in old money).

Of course, if you are making both blades as sub-assembly units, you have a fair bit of freedom with regard to getting the gauge "right". in particular you can gauge both both roads and then set things out so that neither are tight to gauge. Having said that, I think this aspect is always a real challenge for a beginner (and quite a few people at the NAG session would see themselves in that category). For me therefore, there is an advantage in an approach which keeps options open right up until the last moment - with "traditional" rivet construction, the first rail you solder is committed: any subsequent "tweaking" is both difficult and fraught with issues!

Tony W has already done an excellent job of demonstrating the "traditional" approach at NAG and of course Tony has more experience than most of us (put together!) in these matters but - however you build track - there is an awful lot to contend with if you want smooth and reliable running, and I suspect that many people are either frightened off or are disappointed with their efforts. Hence I think it worth exploring some new ideas to help people - even if some ideas fall by the wayside. So again, many thanks for contributing to the debate :thumb

Just in terms of my starting point, I don't believe that plastic chaired track should be built the same way as soldered track yet I have not seen too many write ups on appropriate methods yet! And I am pretty sure my approach is not the definitive answer :D

BTW, still not bitten the bullet on the third rail - but I can't put off the day much longer!

Best Wishes,

Howard.

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Russ Elliott
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Re: Track building with functional plastic chairs

Postby Russ Elliott » Fri Apr 12, 2013 3:09 pm

JFS wrote:Just one question thinking about the geometry however - in the event that both blades were machined perfectly and identically, is the implication of your approach that the straight road would also be over gauge?

Yes, unequivocally. I see no point in attempting to get the straight road exactly to TG if the price to pay for doing that is a potential undergauge problem on the divergent road. In my dotage, I'm beginning to see the wisdom of joggles, although they bring no comfort to non-GWR fans of course.

The only area where overgauging needs to be controlled is the vicinity of the crossing.

A problem for plastic track fans, as reported by several practitioners, is securing the switch-set portion of the stock rail to a one-sided plastic chair. Temperature stressing is likely to break a solvent-only bond, and hence something stronger is required, and those who have resorted to squirting in a bit of superglue into the joint subsequent to discovering bonding breaks after construction will only be adding to any undergauge problems. (Hence the advent of cast brass slidechairs.)

allanferguson
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Re: Track building with functional plastic chairs

Postby allanferguson » Fri Apr 12, 2013 4:44 pm

Could I say that I strongly agree with Russ here. I have always (since I grew up!) advocated that a little overgauge never does any harm, except at the crossing; a little undergauge is always bad.

But, as a bear of little brain, I am confused by these posts. Gauge is the distance between the rails. So how can the straight road, on its own, be "exactly to gauge"?

Allan F

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grovenor-2685
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Re: Track building with functional plastic chairs

Postby grovenor-2685 » Fri Apr 12, 2013 5:17 pm

Gauge is the distance between the rails. So how can the straight road, on its own, be "exactly to gauge"?

Well, if you use the common 3 point track gauge, and assuming perfection in the gauge and the use of it, then the straight road would be exactly to the nominal gauge, the curved road would have a bit of gauge widening depending on the length of the 3 point gauge and the radius of the turnout. Each road has its own pair of rails, hence the gauge need not be identical. At the switch toe the gauge is, of course common, so if you choose to widen it as Russ advocates then both roads are affected. Personally I believe use of the standard recommended P4 settings for BB gives enough tolerance such that there is no need to widen the gauge at the switch toe, normal gauge is fine. It may be a little different if you want to use the increased BB (S4) settings. What is important is to check you don't have any gauge narrowing that can easily creep in through the switch on the curved road.
I went through my construction sequence here http://www.norgrove.me.uk/points.html which is the result of 50 years building turnouts and looks to be pretty similar to the suggestions above.
Regards
Keith

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 5:35 pm

Russ Elliott wrote:Yes, unequivocally.



That is what I thought but I did not want to assume!

Many thanks,

Howard

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 5:48 pm

Russ Elliott wrote:
A problem for plastic track fans, as reported by several practitioners, is securing the switch-set portion of the stock rail to a one-sided plastic chair.


Russ,

I think this is a good example of where following the same construction method as for soldered construction is never going to work. The way I tackle this is to glue the chairs to the rail using a "proper" glue - I use Loctite 435 as it has a high peel strength and testing it to failure results in the chair bending in half before the joint goes. By gluing the chairs to the rail BEFORE attaching the chairs to the timbers avoids the risk of "pushing the gauge in" which - as you say is death to success!

Best wishes,

Howard

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 6:02 pm

Keith,

Many thanks for answering this point.

grovenor-2685 wrote:I went through my construction sequence here http://www.norgrove.me.uk/points.html which is the result of 50 years building turnouts and looks to be pretty similar to the suggestions above.

I can't see any plastic chaired track here - did you post the wrong link??

I have been trying to tell the chaps that methods which work fine with rivets, and which have been very ably demonstrated at NAG by Tony W might lead them into trouble with functional chairs - not least for the kind of reason that Russ refers above. I am not saying those methods are wrong - just that they are designed for a different technology.

It looks like you have three more years experience than I do - I am feeling less old now :D

Best wishes,

Howard.

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Russ Elliott
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Re: Track building with functional plastic chairs

Postby Russ Elliott » Fri Apr 12, 2013 6:16 pm

grovenor-2685 wrote:Well, if you use the common 3 point track gauge, and assuming perfection in the gauge and the use of it, then the straight road would be exactly to the nominal gauge, the curved road would have a bit of gauge widening depending on the length of the 3 point gauge and the radius of the turnout.

Perfection in a 3-point gauge? Hmmm. Can't say I've noticed that in the last 30 years. (Tony Wilkins' trusty Studioliths are a tad over TGnom , btw.)

But even if the artefact is correct, it doesn't cope with this, for which we rely on line of sight when bending 'the set', and the assumption that the set will be perfectly straight over the length of planing (and hence where Howard's off-timber assemblies are at least a step in the right direction):

switch-curve4.png
switch-curve4.png (3.39 KiB) Viewed 4714 times

If every member got issued with a free Exactoscale +0.1 roller with their next Snooze, we might not need to have this discussion :idea:

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 6:37 pm

Russ,

Exactly my point. - You can only measure gauge to the gauge face of a pair of rails!

Free Gauge? Can't have that - I paid for mine and very excellent it is as well.

I mentioned to the group that the first P4 layout I was involved with we built all the track just using a check gauge - it was all we could afford! It did the job of check gauge, track gauge and cf gauge! I don't suggest that as a general approach but it does show that I don't regard nominal gauge as the be all and end all! In truth I have never owned at triangular gauge and I can't say I have missed it!!

Cheers.

Howard.

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 7:06 pm

Well, after all that where were we?

I did talk a bit about ballasting on Tuesday but we did not do any, so here are afew pics showing my approach to that:-

NOTE TO ALL COMERS:- I DO KNOW THERE ARE OTHER WAYS OF DOING THIS.... :D Please feel free to contribute in terms of your experiences with FUNCTIONAL PLASTIC CHAIRS :D

Firstly, the PVA is put in place using an eyedropper - remembering that, for the reasons I gave, the sleepers are 1.6mm thick (and, again sorry about the horrible plastic sleepers - yuk - would never been seen dead using those..!) and you can see that the PVA is deep enough to come to the top of the sleepers.

PVA applied.jpg


I mentioned that for this approach to work, the PVA must be "water proof" grade thinned to single cream consistency with a drop of washing up liquid in about 100ml. Because this is a demo, I am only doing a few inches - on the layout, I was doing about 18" of double track at a time - I won't be recommending this approach to Ray Jackson!

Next the ballast is very gently sprinkled on

Sprinkle Ballast].jpg


Now the job needs leaving for about an hour (checking the time on the images it was nearer an hour and a half.

Now the XS can be shaken off.

Shake off.jpg


And what a mess it looks. But beacuse the glue is still spongy, we can scrape the sleepers clean, the push and stroke the ballast clean and level. If it is too deep between the sleepers, a bit can easily be dug out and the remainder levelled off.

Now here is the issue with the "right" PVA. If you just use the common or garden PVA this approach does not work. If you try it, you will find that when you try to manipulate the ballast, the stuff will have dried to a hard crust whilst still being completly liquid beneath. With the Waterproof stuff, it seems to go pasty all the way through - thus the mass of ballast holds together but is soft enough to be pushed around.

Finally it looks like this

Clean up.jpg


Next job is to build up / clean up the ballast shoulder and tidy up the dreadfull-looking cess!

Hope that helps to show what I was trying to describe.


Cheers,

Howard.

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grovenor-2685
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Re: Track building with functional plastic chairs

Postby grovenor-2685 » Fri Apr 12, 2013 8:29 pm

Perfection in a 3-point gauge?
Yes well I was specifically answering the point about "exact gauge", without those assumptions the gauge will never be exact, just within tolerance, if you are reasonably careful. To avoid narrow gauge opposite the switch you need to fit one switch and stock then gauge the opposite stock rail from it, as in my link and in Russ' diagrams. The alternative of setting the gauge at the end of planing with a loose bit of rail is OK if your switch blade filing is perfect but does not cover for any minor errors, gauging off the switch rail will.
I don't see that it makes any difference in principle whether you are soldering to rivets or using cosmetic chairs, or whether you pre-assemble the half sets as in the P4 track Co. kits and as Howard is suggesting, I have not tried that personally but I can see it could work well, and it is how we do it on the big railway.
Regards
Keith

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Fri Apr 12, 2013 9:09 pm

grovenor-2685 wrote:I don't see that it makes any difference in principle whether you are soldering to rivets or using cosmetic chairs, or whether you pre-assemble the half sets as in the P4 track Co. kits and as Howard is suggesting,


I agree at the level of the principle - and I think we are all pretty much in agreement about what need to happen here - however I think it is just around the nuts and bolts of assembly where the differences emerge. And perhaps where the pitfalls for the unwary are hiding!

Hopefully over the weekend - other demands permitting - I can post a few pics of that aspect then we can all compare notes!!

One challenge we have to bear in mind is around what (in the context of plastic chairs!) would work best for those who lack experience - most of us in this little discussion could probably make any method work because we can work from first principles. Plus the fact that we have made all the cock ups in our long and eventful careers!

Again, I explained on Tuesday that in previous efforts I have used rivets in the switch area and only moved on from that when I was confident that I had a better alternative - which is not to say it won't evolve again.

Just to the reference Russ made to brass slide chairs, one reason for not using them is that there is not (yet) a P4 version but they do offer yet another option at the toe end of switches - though cleaning the investment out of the jaw is a bit of a pain!

Best wishes,

Howard.

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grovenor-2685
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Re: Track building with functional plastic chairs

Postby grovenor-2685 » Fri Apr 12, 2013 11:04 pm

is that there is not (yet) a P4 version

Rather intrigued, never having looked at these, what makes a slide chair P4 or not P4?
Keith

allanferguson
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Re: Track building with functional plastic chairs

Postby allanferguson » Fri Apr 12, 2013 11:17 pm

grovenor-2685 wrote:
Gauge is the distance between the rails. So how can the straight road, on its own, be "exactly to gauge"?

Well, if you use the common 3 point track gauge, and assuming perfection in the gauge and the use of it, then the straight road would be exactly to the nominal gauge, the curved road would have a bit of gauge widening depending on the length of the 3 point gauge and the radius of the turnout. Regards
Keith


:idea: My apologies, I was confusing "rail" and "road". I was confused by the pictures of single switch blades with their stock rails. Back to the bottle.....

Allan F

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Sat Apr 13, 2013 8:47 am

grovenor-2685 wrote:Rather intrigued, never having looked at these, what makes a slide chair P4 or not P4?
Keith


Hi Keith,

The 00/EM chairs have a longer extension to allow for the excessive switch opening that I am told exists in such gauges :D The P4 ones are "exact scale" - little pic to illustrate:-

Slide chairs-1.jpg
Slide chairs-1.jpg (63.34 KiB) Viewed 4625 times


It surprising what a difference it make to the appearance. Needless to say we are talking Exactoscale here.

Hope that clarifies!

Howard

JFS
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Re: Track building with functional plastic chairs

Postby JFS » Sat Apr 13, 2013 1:31 pm

I managed to get half an hour putting things together - I have taken some pics and will post them when I have a mo.

But in the meantime, here is a conundrum which BEGINNERS might like to ponder -

Is this a LEFT hand switch or a RIGHT hand switch? (this is the "other one" - not the one previously posted)

LH Switch.jpg


It clearly curves away to the right, therefore it is a Right hand - yes???

By the way, there is still a lot to do at the above stage (you can see that only a few chairs are stuck down) - there are a few faults on display!


More later,

Howard.

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Russ Elliott
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Re: Track building with functional plastic chairs

Postby Russ Elliott » Sat Apr 13, 2013 2:20 pm

What a tease! It's a left-hand switch that's been bent to the right. I expect Martin will arrive with a severe ticking off soon ;)


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